The intrusion-related Cerro Negro Norte Fe-oxide (Cu-Au) deposit is hosted in andesites and diorites of the early to middle Cretaceous Coastal Cordilleran arc of northern Chile. Tabular and irregularly shaped magnetite orebodies are localized on splays and fractures of the regional NINE striking Atacama Fault Zone. Production from this district was [approximately]100 MT @ [approximately] 65 wt. % Fe. Early Na-Ca alteration assemblages associated with magnetite �� apatite �� pyrite �� chalcopyrite ore include actinolite, marialitic scapolite, oligoclase, titanite, and epidote. Na-Ca alteration is extensive (>4 km�� in area), locally pervasive in the district, and is locally associated with granodiorite dike emplacement. The alkali-rich alteration and sulfide poor mineralization at CNN is characterized by metasomatic exchange of major, minor, and trace elements (added Fe, Na, Ca, Cl, P, Rare Earth Elements) between andesitic and diorite host rocks and halite-saturated saline hydrothermal fluids preserved as inclusions. Intrusion-heated fluids converge along the Atacama Fault Zone, and dikes, and may have been derived either from seawater or evaporitic water trapped in sedimentary rocks of the protoarc. Younger, cross-cutting hydrothermal assemblages such as tourmaline-quartzsericite (�� breccias), associated with granodiorite dikes, and chiorite-calcite-tourmalinequartz assemblages are related to pyrite �� chalcopyrite �� hematite and Cu-Au mineralization. Supergene minerals include goethite, Cu-carbonates and Cu-oxide. Later carbonate (dolomite) alteration is also localized along northeast-striking faults. Inferred Cu-Au estimates are [approximately] 1 MT @ [approximately] 1 g/T Au and 0.25 wt. % Cu. Late alteration assemblages may contain a component of magmatic saline fluids generated by observed monzodiorite-granodiorite dikes and pluton emplacement. Massive magnetite ore and associated Na-Ca alteration assemblages were deposited at high temperatures ( 500 to 6000 C), with igneous intrusions providing heat but not necessarily fluids and metals. Later moderate to low temperature Cu-Au mineralization (sulfide + oxide) replaces magnetite, and records the transition to more brittle faulting, with NW �� re-activated NNE structural control, and a greater proportion of magmatic fluids, sulfur ([delta]�����S[subscriptpy] = -1 0/00), and metals. / Graduation date: 2002

Detailed subsurface structure contour maps and cross sections have shown the northern Los Angeles basin to be underlain by a south facing monocline that is complicated by secondary faults and folds. The monocline forms a structural shelf that marks the northern boundary of the Los Angeles central trough. The monocline and associated structures are called the Northern Los Angeles shelf. Isopach maps show that during the Miocene, the predominant structural style was extension. Thick accumulations of volcanic and volcaniclastic rocks, controlled by normal faults, had a very different depositional pattern than during the Pliocene. At approximately the beginning of the Pliocene extension changed to compression resulting in the reactivation of the Miocene normal faults in a reverse sense and the beginning of the formation of the monocline and secondary structures. Thick growth sequences were deposited to the south of the growing monocline toward the present day Los Angeles central trough. Fault-bend and fault-propagation fold models are inadmissible solutions to explain the growth of the monocline. A basement-involved shear model may explain some of the details of the secondary structures. Analysis of the Pliocene growth strata shows that the monocline and secondary structures, the South Salt Lake, the East Beverly Hills, and the Las Cienegas anticlines, all began to form near the beginning of the Pliocene. All of the secondary structures became inactive prior to the Upper Pico during the Late Pliocene. Thick accumulations of Upper Pico growth strata attest to continued monoclinal folding after the secondary structures became inactive. The growth strata record both the structural growth and the shortening associated with growth and therefore allow the dip of the monocline causing fault or shear zone (the Monocline fault) to be calculated. In the East Beverly Hills area, the growth strata yield a dip of 61°. At Las Cienegas the dip of the Monocline fault is 62°. These dips are maximum values based on the assumption the growth strata record all shortening. The fault slip rates for the Monocline fault are similar in both areas, 1.1-1.2 mm/yr in the East Beverly Hills and 1.3-1.5 mm/yr. in Las Cienegas. The resulting horizontal convergence rates are also similar, .5-.6 mm/yr and .6-.7 mm/yr respectively. The Quaternary marine gravels have been deformed into a broad east-west trending fold, the Wilshire arch. Elastic and non-elastic methods of modeling the blind fault (Wilshire fault), over which the deformation occurred, yield much greater shortening rates than for the Pliocene. The non-elastic method involves modeling the arch as a fault-bend fold. This model predicts a 15° north-dipping thrust with a slip rate of 1.5-1.9 mm/yr and a horizontal shortening rate of 1.4-1.8 mm/yr. The elastic method involves matching the observed deformation to that produced on the free surface by slip on a fault in an elastic half-space. The elastic dislocation model predicts a right-lateral reverse slip solution with an oblique-slip rate of 2.6-3.3 mm/yr. This solution yields a horizontal shortening rate of 1.4-1.8 mm/yr. These higher shortening rates suggest that there was a marked change in tectonic style at the end of the Pliocene from high-angle faulting and tectonic subsidence to shallow faulting and uplift. / Graduation date: 1994

Thesis (Ph.D.)--Memorial University of Newfoundland, 2005. / Bibliography: leaves 273-299. Also available online.

Thesis (M.S.)--Brigham Young University. Dept. of Geology, 2006. / Includes bibliographical references.

Both travel times and amplitudes of large offset refracted and reflected arrivals observed during GLIMPCE (Great Lakes International Multidisciplinary Program on Crustal Evolution) along line A in Lake Superior have been modeled using two-dimensional ray tracing techniques. Forward modeling was used to iteratively refine an initial velocity model that was constructed from results of tau-sum analysis of the travel time data at each station combined with information from the coincident common depth point (CDP) reflection profile. When converted to time the resulting model agrees quite well with the CDP reflection profile. A 50-100 ms time advance anomaly associated with the Isle Royal Fault is observed at every station. This anomaly has been modeled as shallow, high velocity blocks located directly beneath the fault. The blocks correlate well with the walls of a steep-sided bathymetric trough and are believed to represent highly indurated upper Keweenawan sediments which may have resulted from hydrothermal alteration. Approximately 2 km of sedimentary rock (2.8-4.6 km/sec) overlie an 8 km thick sequence of volcanics and interflow sediments (5.0-6.5 km/sec) within the rift graben observed on the reflection data. Beneath this sequence is a 6-8 km thick sequence of 6.6-7.0 km/sec material that is interpreted to represent metamorphosed volcanics. The velocity of the material at the base of the rift graben is not well constrained (approximately 7.0 -7.2 km/sec), but probably comprises an additional 10-12 kilometers of meta-volcanic rocks and intrusions that extend to the base of the graben as imaged on the CDP reflection profile. Boundaries between these sequences are indicated by reflections observed at several of the wide-aperture stations. A marked decrease in the apparent velocity and amplitude of the first arrivals is observed on reversed sections at ranges exceeding 100 km. This decrease in apparent velocity has been modeled as lower velocity continental crustal rocks (approximately 6.5 km/sec) at a depth of about 15-20 km adjacent to the 7.0 km/sec material in the graben. Calculation of the gravity response of the seismic model demonstrates that the gravity high centered over the rift can be entirely attributed to high density rocks occupying the central half-graben imaged on the CDP profile. Wide angle reflections from about 15-30 km depth beneath the flanks of the graben indicate the presence of velocity discontinuities that may represent rift related detachment surfaces and/or pre-rift structures. Modeling of wide angle reflections indicate a high degree of structural relief preserved within the lower crust. The high velocities modeled for this region, coupled with information from the CDP profile, suggest that the lower crust represents Archean crust that has been either heavily intruded or underplated by mafic magma. The style and volume of volcanic emplacement is similar to that of Phanerozoic rifted continental margins and flood basalt provinces. By analogy, the volcanism within the midcontinent rift appears to have resulted from decompression melting during lithospheric extension above a broad, asthenospheric thermal anomaly recently referred to in the literature as the "Keweenawan hot spot". / Graduation date: 1991

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references. Available also from UMI Company.

Thèse--Nancy. / At head of title on added t.p.: Gouvernement général de l'Afrique occidentale française. Service géologique. "Bibliographie": p. 12-16.

Thesis (Ph. D.)--Florida State University, 2003. / Advisor: Dr. Neil Lundberg, Florida State University, College of Arts and Sciences, Dept. of Geological Sciences. Title and description from dissertation home page (viewed Mar. 2, 2004). Includes bibliographical references.

Thesis (M.S.)--Oregon State University, 2002. / Typescript (photocopy). Includes bibliographical references (leaves 42-44). Also available via the World Wide Web.

Thesis (M.A.)--University of Hong Kong, 1961. / Type-written copy. Includes bibliographical references (p. 103-115). Also available on microfilm.